Hydroelectric Power

Hydroelectric power, or hydroelectricity, is generated
by the force of falling water. (Hydro comes from the Greek
word for water.) Its one of the cleanest sources of energy, and
its also the most reliable and costs the least. That means that
TVA’s hydroelectric
power plants are able provide electricity at a reasonable cost
to families, schools, farms, factories and businesses.

How does hydroelectric power work?

Water is needed to run a hydroelectric
power-generating unit. The water is held behind a dam, forming
an artificial lake, or reservoir. The force of the water being released
from the reservoir through the dam spins the blades of a giant turbine.
The turbine is connected to the generator that makes electricity
as it spins. After passing through the turbine, the water flows back
into the river on the other side of the dam.

TVA uses water to make electricity at 29 hydroelectric
dams and one pumped-storage power plant (at Raccoon
Mountain near Chattanooga, Tennessee). Together these plants produced
about 13.9 million megawatt hours of electricity in 2016, enough electricity
to power nearly one million homes for a year.

How
does a pumped-storage plant work?

A pumped-storage
plant uses two reservoirs, one located at a much higher elevation
than the other. During times when people are not using a lot of
electricity, such as nights and weekends, water is pumped from
the lower to the upper reservoir.

Thus,
the water is stored for use during weekdays when people need
more electricity. The stored water can be released to turn the
turbines and generate electricity as it flows back down to the
lower reservoir. Read more about TVA’s Raccoon
Mountain Pumped Storage Plant.